1: Introduction
2: ============
3:
4: [![[Xen
5: screenshot]](http://www.netbsd.org/gallery/in-Action/hubertf-xens.png)](../../gallery/in-Action/hubertf-xen.png)
6:
7: Xen is a virtual machine monitor or hypervisor for x86 hardware
8: (i686-class or higher), which supports running multiple guest
9: operating systems on a single physical machine. With Xen, one uses
10: the Xen kernel to control the CPU, memory and console, a dom0
11: operating system which mediates access to other hardware (e.g., disks,
12: network, USB), and one or more domU operating systems which operate in
13: an unprivileged virtualized environment. IO requests from the domU
14: systems are forwarded by the hypervisor (Xen) to the dom0 to be
15: fulfilled.
16:
17: Xen supports two styles of guests. The original is Para-Virtualized
18: (PV) which means that the guest OS does not attempt to access hardware
19: directly, but instead makes hypercalls to the hypervisor. This is
20: analogous to a user-space program making system calls. (The dom0
21: operating system uses PV calls for some functions, such as updating
22: memory mapping page tables, but has direct hardware access for disk
23: and network.) PV guests must be specifically coded for Xen.
24:
25: The more recent style is HVM, which means that the guest does not have
26: code for Xen and need not be aware that it is running under Xen.
27: Attempts to access hardware registers are trapped and emulated. This
28: style is less efficient but can run unmodified guests.
29:
30: Generally any amd64 machine will work with Xen and PV guests. In
31: theory i386 computers without amd64 support can be used for Xen <=
32: 4.2, but we have no recent reports of this working (this is a hint).
33: For HVM guests, the VT or VMX cpu feature (Intel) or SVM/HVM/VT
34: (amd64) is needed; "cpuctl identify 0" will show this. TODO: Clean up
35: and check the above features.
36:
37: At boot, the dom0 kernel is loaded as a module with Xen as the kernel.
38: The dom0 can start one or more domUs. (Booting is explained in detail
39: in the dom0 section.)
40:
41: NetBSD supports Xen in that it can serve as dom0, be used as a domU,
42: and that Xen kernels and tools are available in pkgsrc. This HOWTO
43: attempts to address both the case of running a NetBSD dom0 on hardware
44: and running domUs under it (NetBSD and other), and also running NetBSD
45: as a domU in a VPS.
46:
47: Some versions of Xen support "PCI passthrough", which means that
48: specific PCI devices can be made available to a specific domU instead
49: of the dom0. This can be useful to let a domU run X11, or access some
50: network interface or other peripheral.
51:
52: Prerequisites
53: -------------
54:
55: Installing NetBSD/Xen is not extremely difficult, but it is more
56: complex than a normal installation of NetBSD.
57: In general, this HOWTO is occasionally overly restrictive about how
58: things must be done, guiding the reader to stay on the established
59: path when there are no known good reasons to stray.
60:
61: This HOWTO presumes a basic familiarity with the Xen system
62: architecture. This HOWTO presumes familiarity with installing NetBSD
63: on i386/amd64 hardware and installing software from pkgsrc.
64: See also the [Xen website](http://www.xenproject.org/).
65:
66: History
67: -------
68:
69: NetBSD used to support Xen2; this has been removed.
70:
71: Before NetBSD's native bootloader could support Xen, the use of
72: grub was recommended. If necessary, see the
73: [old grub information](/ports/xen/howto-grub/).
74:
75: Versions of Xen and NetBSD
76: ==========================
77:
78: Most of the installation concepts and instructions are independent
79: of Xen version and NetBSD version. This section gives advice on
80: which version to choose. Versions not in pkgsrc and older unsupported
81: versions of NetBSD are intentionally ignored.
82:
83: Xen
84: ---
85:
86: In NetBSD, xen is provided in pkgsrc, via matching pairs of packages
87: xenkernel and xentools. We will refer only to the kernel versions,
88: but note that both packages must be installed together and must have
89: matching versions.
90:
91: xenkernel3 and xenkernel33 provide Xen 3.1 and 3.3. These no longer
92: receive security patches and should not be used. Xen 3.1 supports PCI
93: passthrough. Xen 3.1 supports non-PAE on i386.
94:
95: xenkernel41 provides Xen 4.1. This is no longer maintained by Xen,
96: but as of 2014-12 receives backported security patches. It is a
97: reasonable although trailing-edge choice.
98:
99: xenkernel42 provides Xen 4.2. This is maintained by Xen, but old as
100: of 2014-12.
101:
102: Ideally newer versions of Xen will be added to pkgsrc.
103:
104: Note that NetBSD support is called XEN3. It works with 3.1 through
105: 4.2 because the hypercall interface has been stable.
106:
107: Xen command program
108: -------------------
109:
110: Early Xen used a program called "xm" to manipulate the system from the
111: dom0. Starting in 4.1, a replacement program with similar behavior
112: called "xl" is provided. In 4.2 and later, "xl" is preferred. 4.4 is
113: the last version that has "xm".
114:
115: NetBSD
116: ------
117:
118: The netbsd-5, netbsd-6, netbsd-7, and -current branches are all
119: reasonable choices, with more or less the same considerations for
120: non-Xen use. Therefore, netbsd-6 is recommended as the stable version
121: of the most recent release for production use. For those wanting to
122: learn Xen or without production stability concerns, netbsd-7 is likely
123: most appropriate.
124:
125: As of NetBSD 6, a NetBSD domU will support multiple vcpus. There is
126: no SMP support for NetBSD as dom0. (The dom0 itself doesn't really
127: need SMP; the lack of support is really a problem when using a dom0 as
128: a normal computer.)
129:
130: Architecture
131: ------------
132:
133: Xen itself can run on i386 or amd64 machines. (Practically, almost
134: any computer where one would want to run Xen supports amd64.) If
135: using an i386 NetBSD kernel for the dom0, PAE is required (PAE
136: versions are built by default). While i386 dom0 works fine, amd64 is
137: recommended as more normal.
138:
139: Xen 4.2 is the last version to support i386 as a host. TODO: Clarify
140: if this is about the CPU having to be amd64, or about the dom0 kernel
141: having to be amd64.
142:
143: One can then run i386 domUs and amd64 domUs, in any combination. If
144: running an i386 NetBSD kernel as a domU, the PAE version is required.
145: (Note that emacs (at least) fails if run on i386 with PAE when built
146: without, and vice versa, presumably due to bugs in the undump code.)
147:
148: Recommendation
149: --------------
150:
151: Therefore, this HOWTO recommends running xenkernel42 (and xentools42),
152: xl, the NetBSD 6 stable branch, and to use an amd64 kernel as the
153: dom0. Either the i386 or amd64 of NetBSD may be used as domUs.
154:
155: Build problems
156: --------------
157:
158: Ideally, all versions of Xen in pkgsrc would build on all versions of
159: NetBSD on both i386 and amd64. However, that isn't the case. Besides
160: aging code and aging compilers, qemu (included in xentools for HVM
161: support) is difficult to build. The following are known to fail:
162:
163: xenkernel3 netbsd-6 i386
164: xentools42 netbsd-6 i386
165:
166: The following are known to work:
167:
168: xenkernel41 netbsd-5 amd64
169: xentools41 netbsd-5 amd64
170: xenkernel41 netbsd-6 i386
171: xentools41 netbsd-6 i386
172:
173: NetBSD as a dom0
174: ================
175:
176: NetBSD can be used as a dom0 and works very well. The following
177: sections address installation, updating NetBSD, and updating Xen.
178: Note that it doesn't make sense to talk about installing a dom0 OS
179: without also installing Xen itself. We first address installing
180: NetBSD, which is not yet a dom0, and then adding Xen, pivoting the
181: NetBSD install to a dom0 install by just changing the kernel and boot
182: configuration.
183:
184: Styles of dom0 operation
185: ------------------------
186:
187: There are two basic ways to use Xen. The traditional method is for
188: the dom0 to do absolutely nothing other than providing support to some
189: number of domUs. Such a system was probably installed for the sole
190: purpose of hosting domUs, and sits in a server room on a UPS.
191:
192: The other way is to put Xen under a normal-usage computer, so that the
193: dom0 is what the computer would have been without Xen, perhaps a
194: desktop or laptop. Then, one can run domUs at will. Purists will
195: deride this as less secure than the previous approach, and for a
196: computer whose purpose is to run domUs, they are right. But Xen and a
197: dom0 (without domUs) is not meaingfully less secure than the same
198: things running without Xen. One can boot Xen or boot regular NetBSD
199: alternately with little problems, simply refraining from starting the
200: Xen daemons when not running Xen.
201:
202: Note that NetBSD as dom0 does not support multiple CPUs. This will
203: limit the performance of the Xen/dom0 workstation approach.
204:
205: Installation of NetBSD
206: ----------------------
207:
208: First,
209: [install NetBSD/amd64](/guide/inst/)
210: just as you would if you were not using Xen.
211: However, the partitioning approach is very important.
212:
213: If you want to use RAIDframe for the dom0, there are no special issues
214: for Xen. Typically one provides RAID storage for the dom0, and the
215: domU systems are unaware of RAID. The 2nd-stage loader bootxx_* skips
216: over a RAID1 header to find /boot from a filesystem within a RAID
217: partition; this is no different when booting Xen.
218:
219: There are 4 styles of providing backing storage for the virtual disks
220: used by domUs: raw partitions, LVM, file-backed vnd(4), and SAN,
221:
222: With raw partitions, one has a disklabel (or gpt) partition sized for
223: each virtual disk to be used by the domU. (If you are able to predict
224: how domU usage will evolve, please add an explanation to the HOWTO.
225: Seriously, needs tend to change over time.)
226:
227: One can use [lvm(8)](/guide/lvm/) to create logical devices to use
228: for domU disks. This is almost as efficient as raw disk partitions
229: and more flexible. Hence raw disk partitions should typically not
230: be used.
231:
232: One can use files in the dom0 filesystem, typically created by dd'ing
233: /dev/zero to create a specific size. This is somewhat less efficient,
234: but very convenient, as one can cp the files for backup, or move them
235: between dom0 hosts.
236:
237: Finally, in theory one can place the files backing the domU disks in a
238: SAN. (This is an invitation for someone who has done this to add a
239: HOWTO page.)
240:
241: Installation of Xen
242: -------------------
243:
244: In the dom0, install sysutils/xenkernel42 and sysutils/xentools42 from
245: pkgsrc (or another matching pair).
246: See [the pkgsrc
247: documentation](http://www.NetBSD.org/docs/pkgsrc/) for help with pkgsrc.
248:
249: For Xen 3.1, support for HVM guests is in sysutils/xentool3-hvm. More
250: recent versions have HVM support integrated in the main xentools
251: package. It is entirely reasonable to run only PV guests.
252:
253: Next you need to install the selected Xen kernel itself, which is
254: installed by pkgsrc as "/usr/pkg/xen*-kernel/xen.gz". Copy it to /.
255: For debugging, one may copy xen-debug.gz; this is conceptually similar
256: to DIAGNOSTIC and DEBUG in NetBSD. xen-debug.gz is basically only
257: useful with a serial console. Then, place a NetBSD XEN3_DOM0 kernel
258: in /, copied from releasedir/amd64/binary/kernel/netbsd-XEN3_DOM0.gz
259: of a NetBSD build. Both xen and NetBSD may be left compressed. (If
260: using i386, use releasedir/i386/binary/kernel/netbsd-XEN3PAE_DOM0.gz.)
261:
262: In a dom0 kernel, kernfs is mandatory for xend to comunicate with the
263: kernel, so ensure that /kern is in fstab.
264:
265: Because you already installed NetBSD, you have a working boot setup
266: with an MBR bootblock, either bootxx_ffsv1 or bootxx_ffsv2 at the
267: beginning of your root filesystem, /boot present, and likely
268: /boot.cfg. (If not, fix before continuing!)
269:
270: See boot.cfg(5) for an example. The basic line is
271:
272: menu=Xen:load /netbsd-XEN3_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=256M
273:
274: which specifies that the dom0 should have 256M, leaving the rest to be
275: allocated for domUs. In an attempt to add performance, one can also
276: add
277:
278: dom0_max_vcpus=1 dom0_vcpus_pin
279:
280: to force only one vcpu to be provided (since NetBSD dom0 can't use
281: more) and to pin that vcpu to a physical cpu. TODO: benchmark this.
282:
283: As with non-Xen systems, you should have a line to boot /netbsd (a
284: kernel that works without Xen) and fallback versions of the non-Xen
285: kernel, Xen, and the dom0 kernel.
286:
287: The [HowTo on Installing into
288: RAID-1](http://mail-index.NetBSD.org/port-xen/2006/03/01/0010.html)
289: explains how to set up booting a dom0 with Xen using grub with
290: NetBSD's RAIDframe. (This is obsolete with the use of NetBSD's native
291: boot.)
292:
293: Configuring Xen
294: ---------------
295:
296: Now, you have a system that will boot Xen and the dom0 kernel, and
297: just run the dom0 kernel. There will be no domUs, and none can be
298: started because you still have to configure the dom0 tools. The
299: daemons which should be run vary with Xen version and with whether one
300: is using xm or xl. Note that xend is for supporting "xm", and should
301: only be used if you plan on using "xm". Do NOT enable xend if you
302: plan on using "xl" as it will cause problems.
303:
304: TODO: Give 3.1 advice (or remove it from pkgsrc).
305:
306: For 3.3 (and thus xm), add to rc.conf (but note that you should have
307: installed 4.1 or 4.2):
308:
309: xend=YES
310: xenbackendd=YES
311:
312: For 4.1 (and thus xm; xl is believed not to work well), add to rc.conf:
313:
314: xend=YES
315: xencommons=YES
316:
317: TODO: Explain why if xm is preferred on 4.1, rc.d/xendomains has xl.
318: Or fix the package.
319:
320: For 4.2 with xm, add to rc.conf
321:
322: xend=YES
323: xencommons=YES
324:
325: For 4.2 with xl (preferred), add to rc.conf:
326:
327: TODO: explain if there is a xend replacement
328: xencommons=YES
329:
330: TODO: Recommend for/against xen-watchdog.
331:
332: After you have configured the daemons and rebooted, run the following
333: (or use xl) to inspect Xen's boot messages, available resources, and
334: running domains:
335:
336: xm dmesg
337: xm info
338: xm list
339:
340: anita (for testing NetBSD)
341: --------------------------
342:
343: With the setup so far, one should be able to run anita (see
344: pkgsrc/sysutils/py-anita) to test NetBSD releases, by doing (as root,
345: because anita must create a domU):
346:
347: anita --vmm=xm test file:///usr/obj/i386/
348:
349: Alternatively, one can use --vmm=xl to use xl-based domU creation instead.
350: TODO: check this.
351:
352: Xen-specific NetBSD issues
353: --------------------------
354:
355: There are (at least) two additional things different about NetBSD as a
356: dom0 kernel compared to hardware.
357:
358: One is that modules are not usable in DOM0 kernels, so one must
359: compile in what's needed. It's not really that modules cannot work,
360: but that modules must be built for XEN3_DOM0 because some of the
361: defines change and the normal module builds don't do this. Basically,
362: enabling Xen changes the kernel ABI, and the module build system
363: doesn't cope with this.
364:
365: The other difference is that XEN3_DOM0 does not have exactly the same
366: options as GENERIC. While it is debatable whether or not this is a
367: bug, users should be aware of this and can simply add missing config
368: items if desired.
369:
370: Updating NetBSD in a dom0
371: -------------------------
372:
373: This is just like updating NetBSD on bare hardware, assuming the new
374: version supports the version of Xen you are running. Generally, one
375: replaces the kernel and reboots, and then overlays userland binaries
376: and adjusts /etc.
377:
378: Note that one must update both the non-Xen kernel typically used for
379: rescue purposes and the DOM0 kernel used with Xen.
380:
381: To convert from grub to /boot, install an mbr bootblock with fdisk,
382: bootxx_ with installboot, /boot and /boot.cfg. This really should be
383: no different than completely reinstalling boot blocks on a non-Xen
384: system.
385:
386: Updating Xen versions
387: ---------------------
388:
389: Updating Xen is conceptually not difficult, but can run into all the
390: issues found when installing Xen. Assuming migration from 4.1 to 4.2,
391: remove the xenkernel41 and xentools41 packages and install the
392: xenkernel42 and xentools42 packages. Copy the 4.2 xen.gz to /.
393:
394: Ensure that the contents of /etc/rc.d/xen* are correct. Enable the
395: correct set of daemons. Ensure that the domU config files are valid
396: for the new version.
397:
398:
399: Unprivileged domains (domU)
400: ===========================
401:
402: This section describes general concepts about domUs. It does not
403: address specific domU operating systems or how to install them. The
404: config files for domUs are typically in /usr/pkg/etc/xen, and are
405: typically named so that the file anme, domU name and the domU's host
406: name match.
407:
408: The domU is provided with cpu and memory by Xen, configured by the
409: dom0. The domU is provided with disk and network by the dom0,
410: mediated by Xen, and configured in the dom0.
411:
412: Entropy in domUs can be an issue; physical disks and network are on
413: the dom0. NetBSD's /dev/random system works, but is often challenged.
414:
415: CPU and memory
416: --------------
417:
418: A domain is provided with some number of vcpus, less than the
419: number of cpus seen by the hypervisor. For a dom0, this is controlled
420: by the boot argument "dom0_max_vcpus=1". For a domU, it is controlled
421: from the config file.
422:
423: A domain is provided with memory, In the straightforward case, the sum
424: of the the memory allocated to the dom0 and all domUs must be less
425: than the available memory.
426:
427: Xen also provides a "balloon" driver, which can be used to let domains
428: use more memory temporarily. TODO: Explain better, and explain how
429: well it works with NetBSD.
430:
431: Virtual disks
432: -------------
433:
434: With the file/vnd style, typically one creates a directory,
435: e.g. /u0/xen, on a disk large enough to hold virtual disks for all
436: domUs. Then, for each domU disk, one writes zeros to a file that then
437: serves to hold the virtual disk's bits; a suggested name is foo-xbd0
438: for the first virtual disk for the domU called foo. Writing zeros to
439: the file serves two purposes. One is that preallocating the contents
440: improves performance. The other is that vnd on sparse files has
441: failed to work. TODO: give working/notworking NetBSD versions for
442: sparse vnd. Note that the use of file/vnd for Xen is not really
443: different than creating a file-backed virtual disk for some other
444: purpose, except that xentools handles the vnconfig commands. To
445: create an empty 4G virtual disk, simply do
446:
447: dd if=/dev/zero of=foo-xbd0 bs=1m count=4096
448:
449: With the lvm style, one creates logical devices. They are then used
450: similarly to vnds.
451:
452: Virtual Networking
453: ------------------
454:
455: TODO: explain xvif concept, and that it's general.
456:
457: There are two normal styles: bridging and NAT.
458:
459: With bridging, the domU perceives itself to be on the same network as
460: the dom0. For server virtualization, this is usually best.
461:
462: With NAT, the domU perceives itself to be behind a NAT running on the
463: dom0. This is often appropriate when running Xen on a workstation.
464:
465: One can construct arbitrary other configurations, but there is no
466: script support.
467:
468: Sizing domains
469: --------------
470:
471: Modern x86 hardware has vast amounts of resources. However, many
472: virtual servers can function just fine on far less. A system with
473: 256M of RAM and a 4G disk can be a reasonable choice. Note that it is
474: far easier to adjust virtual resources than physical ones. For
475: memory, it's just a config file edit and a reboot. For disk, one can
476: create a new file and vnconfig it (or lvm), and then dump/restore,
477: just like updating physical disks, but without having to be there and
478: without those pesky connectors.
479:
480: domU kernels
481: ------------
482:
483: On a physical computer, the BIOS reads sector 0, and a chain of boot
484: loaders finds and loads a kernel. Normally this comes from the root
485: filesystem. With Xen domUs, the process is totally different. The
486: normal path is for the domU kernel to be a file in the dom0's
487: filesystem. At the request of the dom0, Xen loads that kernel into a
488: new domU instance and starts execution. While domU kernels can be
489: anyplace, reasonable places to store domU kernels on the dom0 are in /
490: (so they are near the dom0 kernel), in /usr/pkg/etc/xen (near the
491: config files), or in /u0/xen (where the vdisks are).
492:
493: See the VPS section near the end for discussion of alternate ways to
494: obtain domU kernels.
495:
496: Config files
497: ------------
498:
499: TODO: give example config files. Use both lvm and vnd.
500:
501: TODO: explain the mess with 3 arguments for disks and how to cope (0x1).
502:
503: Starting domains
504: ----------------
505:
506: TODO: Explain "xm start" and "xl start". Explain rc.d/xendomains.
507:
508: TODO: Explain why 4.1 rc.d/xendomains has xl, when one should use xm
509: on 4.1.
510:
511: Creating specific unprivileged domains (domU)
512: =============================================
513:
514: Creating domUs is almost entirely independent of operating system. We
515: first explain NetBSD, and then differences for Linux and Solaris.
516:
517: Creating an unprivileged NetBSD domain (domU)
518: ---------------------------------------------
519:
520: Once you have *domain0* running, you need to start the xen tool daemon
521: (`/usr/pkg/share/examples/rc.d/xend start`) and the xen backend daemon
522: (`/usr/pkg/share/examples/rc.d/xenbackendd start` for Xen3\*,
523: `/usr/pkg/share/examples/rc.d/xencommons start` for Xen4.\*). Make sure
524: that `/dev/xencons` and `/dev/xenevt` exist before starting `xend`. You
525: can create them with this command:
526:
527: # cd /dev && sh MAKEDEV xen
528:
529: xend will write logs to `/var/log/xend.log` and
530: `/var/log/xend-debug.log`. You can then control xen with the xm tool.
531: 'xm list' will show something like:
532:
533: # xm list
534: Name Id Mem(MB) CPU State Time(s) Console
535: Domain-0 0 64 0 r---- 58.1
536:
537: 'xm create' allows you to create a new domain. It uses a config file in
538: PKG\_SYSCONFDIR for its parameters. By default, this file will be in
539: `/usr/pkg/etc/xen/`. On creation, a kernel has to be specified, which
540: will be executed in the new domain (this kernel is in the *domain0* file
541: system, not on the new domain virtual disk; but please note, you should
542: install the same kernel into *domainU* as `/netbsd` in order to make
543: your system tools, like savecore(8), work). A suitable kernel is
544: provided as part of the i386 and amd64 binary sets: XEN3\_DOMU.
545:
546: Here is an /usr/pkg/etc/xen/nbsd example config file:
547:
548: # -*- mode: python; -*-
549: #============================================================================
550: # Python defaults setup for 'xm create'.
551: # Edit this file to reflect the configuration of your system.
552: #============================================================================
553:
554: #----------------------------------------------------------------------------
555: # Kernel image file. This kernel will be loaded in the new domain.
556: kernel = "/home/bouyer/netbsd-XEN3_DOMU"
557: #kernel = "/home/bouyer/netbsd-INSTALL_XEN3_DOMU"
558:
559: # Memory allocation (in megabytes) for the new domain.
560: memory = 128
561:
562: # A handy name for your new domain. This will appear in 'xm list',
563: # and you can use this as parameters for xm in place of the domain
564: # number. All domains must have different names.
565: #
566: name = "nbsd"
567:
568: # The number of virtual CPUs this domain has.
569: #
570: vcpus = 1
571:
572: #----------------------------------------------------------------------------
573: # Define network interfaces for the new domain.
574:
575: # Number of network interfaces (must be at least 1). Default is 1.
576: nics = 1
577:
578: # Define MAC and/or bridge for the network interfaces.
579: #
580: # The MAC address specified in ``mac'' is the one used for the interface
581: # in the new domain. The interface in domain0 will use this address XOR'd
582: # with 00:00:00:01:00:00 (i.e. aa:00:00:51:02:f0 in our example). Random
583: # MACs are assigned if not given.
584: #
585: # ``bridge'' is a required parameter, which will be passed to the
586: # vif-script called by xend(8) when a new domain is created to configure
587: # the new xvif interface in domain0.
588: #
589: # In this example, the xvif is added to bridge0, which should have been
590: # set up prior to the new domain being created -- either in the
591: # ``network'' script or using a /etc/ifconfig.bridge0 file.
592: #
593: vif = [ 'mac=aa:00:00:50:02:f0, bridge=bridge0' ]
594:
595: #----------------------------------------------------------------------------
596: # Define the disk devices you want the domain to have access to, and
597: # what you want them accessible as.
598: #
599: # Each disk entry is of the form:
600: #
601: # phy:DEV,VDEV,MODE
602: #
603: # where DEV is the device, VDEV is the device name the domain will see,
604: # and MODE is r for read-only, w for read-write. You can also create
605: # file-backed domains using disk entries of the form:
606: #
607: # file:PATH,VDEV,MODE
608: #
609: # where PATH is the path to the file used as the virtual disk, and VDEV
610: # and MODE have the same meaning as for ``phy'' devices.
611: #
612: # VDEV doesn't really matter for a NetBSD guest OS (it's just used as an index),
613: # but it does for Linux.
614: # Worse, the device has to exist in /dev/ of domain0, because xm will
615: # try to stat() it. This means that in order to load a Linux guest OS
616: # from a NetBSD domain0, you'll have to create /dev/hda1, /dev/hda2, ...
617: # on domain0, with the major/minor from Linux :(
618: # Alternatively it's possible to specify the device number in hex,
619: # e.g. 0x301 for /dev/hda1, 0x302 for /dev/hda2, etc ...
620:
621: disk = [ 'phy:/dev/wd0e,0x1,w' ]
622: #disk = [ 'file:/var/xen/nbsd-disk,0x01,w' ]
623: #disk = [ 'file:/var/xen/nbsd-disk,0x301,w' ]
624:
625: #----------------------------------------------------------------------------
626: # Set the kernel command line for the new domain.
627:
628: # Set root device. This one does matter for NetBSD
629: root = "xbd0"
630: # extra parameters passed to the kernel
631: # this is where you can set boot flags like -s, -a, etc ...
632: #extra = ""
633:
634: #----------------------------------------------------------------------------
635: # Set according to whether you want the domain restarted when it exits.
636: # The default is False.
637: #autorestart = True
638:
639: # end of nbsd config file ====================================================
640:
641: When a new domain is created, xen calls the
642: `/usr/pkg/etc/xen/vif-bridge` script for each virtual network interface
643: created in *domain0*. This can be used to automatically configure the
644: xvif?.? interfaces in *domain0*. In our example, these will be bridged
645: with the bridge0 device in *domain0*, but the bridge has to exist first.
646: To do this, create the file `/etc/ifconfig.bridge0` and make it look
647: like this:
648:
649: create
650: !brconfig $int add ex0 up
651:
652: (replace `ex0` with the name of your physical interface). Then bridge0
653: will be created on boot. See the bridge(4) man page for details.
654:
655: So, here is a suitable `/usr/pkg/etc/xen/vif-bridge` for xvif?.? (a
656: working vif-bridge is also provided with xentools20) configuring:
657:
658: #!/bin/sh
659: #============================================================================
660: # $NetBSD: howto.mdwn,v 1.41 2014/12/26 13:04:31 gdt Exp $
661: #
662: # /usr/pkg/etc/xen/vif-bridge
663: #
664: # Script for configuring a vif in bridged mode with a dom0 interface.
665: # The xend(8) daemon calls a vif script when bringing a vif up or down.
666: # The script name to use is defined in /usr/pkg/etc/xen/xend-config.sxp
667: # in the ``vif-script'' field.
668: #
669: # Usage: vif-bridge up|down [var=value ...]
670: #
671: # Actions:
672: # up Adds the vif interface to the bridge.
673: # down Removes the vif interface from the bridge.
674: #
675: # Variables:
676: # domain name of the domain the interface is on (required).
677: # vifq vif interface name (required).
678: # mac vif MAC address (required).
679: # bridge bridge to add the vif to (required).
680: #
681: # Example invocation:
682: #
683: # vif-bridge up domain=VM1 vif=xvif1.0 mac="ee:14:01:d0:ec:af" bridge=bridge0
684: #
685: #============================================================================
686:
687: # Exit if anything goes wrong
688: set -e
689:
690: echo "vif-bridge $*"
691:
692: # Operation name.
693: OP=$1; shift
694:
695: # Pull variables in args into environment
696: for arg ; do export "${arg}" ; done
697:
698: # Required parameters. Fail if not set.
699: domain=${domain:?}
700: vif=${vif:?}
701: mac=${mac:?}
702: bridge=${bridge:?}
703:
704: # Optional parameters. Set defaults.
705: ip=${ip:-''} # default to null (do nothing)
706:
707: # Are we going up or down?
708: case $OP in
709: up) brcmd='add' ;;
710: down) brcmd='delete' ;;
711: *)
712: echo 'Invalid command: ' $OP
713: echo 'Valid commands are: up, down'
714: exit 1
715: ;;
716: esac
717:
718: # Don't do anything if the bridge is "null".
719: if [ "${bridge}" = "null" ] ; then
720: exit
721: fi
722:
723: # Don't do anything if the bridge doesn't exist.
724: if ! ifconfig -l | grep "${bridge}" >/dev/null; then
725: exit
726: fi
727:
728: # Add/remove vif to/from bridge.
729: ifconfig x${vif} $OP
730: brconfig ${bridge} ${brcmd} x${vif}
731:
732: Now, running
733:
734: xm create -c /usr/pkg/etc/xen/nbsd
735:
736: should create a domain and load a NetBSD kernel in it. (Note: `-c`
737: causes xm to connect to the domain's console once created.) The kernel
738: will try to find its root file system on xbd0 (i.e., wd0e) which hasn't
739: been created yet. wd0e will be seen as a disk device in the new domain,
740: so it will be 'sub-partitioned'. We could attach a ccd to wd0e in
741: *domain0* and partition it, newfs and extract the NetBSD/i386 or amd64
742: tarballs there, but there's an easier way: load the
743: `netbsd-INSTALL_XEN3_DOMU` kernel provided in the NetBSD binary sets.
744: Like other install kernels, it contains a ramdisk with sysinst, so you
745: can install NetBSD using sysinst on your new domain.
746:
747: If you want to install NetBSD/Xen with a CDROM image, the following line
748: should be used in the `/usr/pkg/etc/xen/nbsd` file:
749:
750: disk = [ 'phy:/dev/wd0e,0x1,w', 'phy:/dev/cd0a,0x2,r' ]
751:
752: After booting the domain, the option to install via CDROM may be
753: selected. The CDROM device should be changed to `xbd1d`.
754:
755: Once done installing, `halt -p` the new domain (don't reboot or halt, it
756: would reload the INSTALL\_XEN3\_DOMU kernel even if you changed the
757: config file), switch the config file back to the XEN3\_DOMU kernel, and
758: start the new domain again. Now it should be able to use `root on xbd0a`
759: and you should have a second, functional NetBSD system on your xen
760: installation.
761:
762: When the new domain is booting you'll see some warnings about *wscons*
763: and the pseudo-terminals. These can be fixed by editing the files
764: `/etc/ttys` and `/etc/wscons.conf`. You must disable all terminals in
765: `/etc/ttys`, except *console*, like this:
766:
767: console "/usr/libexec/getty Pc" vt100 on secure
768: ttyE0 "/usr/libexec/getty Pc" vt220 off secure
769: ttyE1 "/usr/libexec/getty Pc" vt220 off secure
770: ttyE2 "/usr/libexec/getty Pc" vt220 off secure
771: ttyE3 "/usr/libexec/getty Pc" vt220 off secure
772:
773: Finally, all screens must be commented out from `/etc/wscons.conf`.
774:
775: It is also desirable to add
776:
777: powerd=YES
778:
779: in rc.conf. This way, the domain will be properly shut down if
780: `xm shutdown -R` or `xm shutdown -H` is used on the domain0.
781:
782: Your domain should be now ready to work, enjoy.
783:
784: Creating an unprivileged Linux domain (domU)
785: --------------------------------------------
786:
787: Creating unprivileged Linux domains isn't much different from
788: unprivileged NetBSD domains, but there are some details to know.
789:
790: First, the second parameter passed to the disk declaration (the '0x1' in
791: the example below)
792:
793: disk = [ 'phy:/dev/wd0e,0x1,w' ]
794:
795: does matter to Linux. It wants a Linux device number here (e.g. 0x300
796: for hda). Linux builds device numbers as: (major \<\< 8 + minor). So,
797: hda1 which has major 3 and minor 1 on a Linux system will have device
798: number 0x301. Alternatively, devices names can be used (hda, hdb, ...)
799: as xentools has a table to map these names to devices numbers. To export
800: a partition to a Linux guest we can use:
801:
802: disk = [ 'phy:/dev/wd0e,0x300,w' ]
803: root = "/dev/hda1 ro"
804:
805: and it will appear as /dev/hda on the Linux system, and be used as root
806: partition.
807:
808: To install the Linux system on the partition to be exported to the guest
809: domain, the following method can be used: install sysutils/e2fsprogs
810: from pkgsrc. Use mke2fs to format the partition that will be the root
811: partition of your Linux domain, and mount it. Then copy the files from a
812: working Linux system, make adjustments in `/etc` (fstab, network
813: config). It should also be possible to extract binary packages such as
814: .rpm or .deb directly to the mounted partition using the appropriate
815: tool, possibly running under NetBSD's Linux emulation. Once the
816: filesystem has been populated, umount it. If desirable, the filesystem
817: can be converted to ext3 using tune2fs -j. It should now be possible to
818: boot the Linux guest domain, using one of the vmlinuz-\*-xenU kernels
819: available in the Xen binary distribution.
820:
821: To get the linux console right, you need to add:
822:
823: extra = "xencons=tty1"
824:
825: to your configuration since not all linux distributions auto-attach a
826: tty to the xen console.
827:
828: Creating an unprivileged Solaris domain (domU)
829: ----------------------------------------------
830:
831: Download an Opensolaris [release](http://opensolaris.org/os/downloads/)
832: or [development snapshot](http://genunix.org/) DVD image. Attach the DVD
833: image to a MAN.VND.4 device. Copy the kernel and ramdisk filesystem
834: image to your dom0 filesystem.
835:
836: dom0# mkdir /root/solaris
837: dom0# vnconfig vnd0 osol-1002-124-x86.iso
838: dom0# mount /dev/vnd0a /mnt
839:
840: ## for a 64-bit guest
841: dom0# cp /mnt/boot/amd64/x86.microroot /root/solaris
842: dom0# cp /mnt/platform/i86xpv/kernel/amd64/unix /root/solaris
843:
844: ## for a 32-bit guest
845: dom0# cp /mnt/boot/x86.microroot /root/solaris
846: dom0# cp /mnt/platform/i86xpv/kernel/unix /root/solaris
847:
848: dom0# umount /mnt
849:
850:
851: Keep the MAN.VND.4 configured. For some reason the boot process stalls
852: unless the DVD image is attached to the guest as a "phy" device. Create
853: an initial configuration file with the following contents. Substitute
854: */dev/wd0k* with an empty partition at least 8 GB large.
855:
856: memory = 640
857: name = 'solaris'
858: disk = [ 'phy:/dev/wd0k,0,w' ]
859: disk += [ 'phy:/dev/vnd0d,6:cdrom,r' ]
860: vif = [ 'bridge=bridge0' ]
861: kernel = '/root/solaris/unix'
862: ramdisk = '/root/solaris/x86.microroot'
863: # for a 64-bit guest
864: extra = '/platform/i86xpv/kernel/amd64/unix - nowin -B install_media=cdrom'
865: # for a 32-bit guest
866: #extra = '/platform/i86xpv/kernel/unix - nowin -B install_media=cdrom'
867:
868:
869: Start the guest.
870:
871: dom0# xm create -c solaris.cfg
872: Started domain solaris
873: v3.3.2 chgset 'unavailable'
874: SunOS Release 5.11 Version snv_124 64-bit
875: Copyright 1983-2009 Sun Microsystems, Inc. All rights reserved.
876: Use is subject to license terms.
877: Hostname: opensolaris
878: Remounting root read/write
879: Probing for device nodes ...
880: WARNING: emlxs: ddi_modopen drv/fct failed: err 2
881: Preparing live image for use
882: Done mounting Live image
883:
884:
885: Make sure the network is configured. Note that it can take a minute for
886: the xnf0 interface to appear.
887:
888: opensolaris console login: jack
889: Password: jack
890: Sun Microsystems Inc. SunOS 5.11 snv_124 November 2008
891: jack@opensolaris:~$ pfexec sh
892: sh-3.2# ifconfig -a
893: sh-3.2# exit
894:
895:
896: Set a password for VNC and start the VNC server which provides the X11
897: display where the installation program runs.
898:
899: jack@opensolaris:~$ vncpasswd
900: Password: solaris
901: Verify: solaris
902: jack@opensolaris:~$ cp .Xclients .vnc/xstartup
903: jack@opensolaris:~$ vncserver :1
904:
905:
906: From a remote machine connect to the VNC server. Use `ifconfig xnf0` on
907: the guest to find the correct IP address to use.
908:
909: remote$ vncviewer 172.18.2.99:1
910:
911:
912: It is also possible to launch the installation on a remote X11 display.
913:
914: jack@opensolaris:~$ export DISPLAY=172.18.1.1:0
915: jack@opensolaris:~$ pfexec gui-install
916:
917:
918: After the GUI installation is complete you will be asked to reboot.
919: Before that you need to determine the ZFS ID for the new boot filesystem
920: and update the configuration file accordingly. Return to the guest
921: console.
922:
923: jack@opensolaris:~$ pfexec zdb -vvv rpool | grep bootfs
924: bootfs = 43
925: ^C
926: jack@opensolaris:~$
927:
928:
929: The final configuration file should look like this. Note in particular
930: the last line.
931:
932: memory = 640
933: name = 'solaris'
934: disk = [ 'phy:/dev/wd0k,0,w' ]
935: vif = [ 'bridge=bridge0' ]
936: kernel = '/root/solaris/unix'
937: ramdisk = '/root/solaris/x86.microroot'
938: extra = '/platform/i86xpv/kernel/amd64/unix -B zfs-bootfs=rpool/43,bootpath="/xpvd/xdf@0:a"'
939:
940:
941: Restart the guest to verify it works correctly.
942:
943: dom0# xm destroy solaris
944: dom0# xm create -c solaris.cfg
945: Using config file "./solaris.cfg".
946: v3.3.2 chgset 'unavailable'
947: Started domain solaris
948: SunOS Release 5.11 Version snv_124 64-bit
949: Copyright 1983-2009 Sun Microsystems, Inc. All rights reserved.
950: Use is subject to license terms.
951: WARNING: emlxs: ddi_modopen drv/fct failed: err 2
952: Hostname: osol
953: Configuring devices.
954: Loading smf(5) service descriptions: 160/160
955: svccfg import warnings. See /var/svc/log/system-manifest-import:default.log .
956: Reading ZFS config: done.
957: Mounting ZFS filesystems: (6/6)
958: Creating new rsa public/private host key pair
959: Creating new dsa public/private host key pair
960:
961: osol console login:
962:
963:
964: Using PCI devices in guest domains
965: ----------------------------------
966:
967: The domain0 can give other domains access to selected PCI devices. This
968: can allow, for example, a non-privileged domain to have access to a
969: physical network interface or disk controller. However, keep in mind
970: that giving a domain access to a PCI device most likely will give the
971: domain read/write access to the whole physical memory, as PCs don't have
972: an IOMMU to restrict memory access to DMA-capable device. Also, it's not
973: possible to export ISA devices to non-domain0 domains (which means that
974: the primary VGA adapter can't be exported. A guest domain trying to
975: access the VGA registers will panic).
976:
977: This functionality is only available in NetBSD-5.1 (and later) domain0
978: and domU. If the domain0 is NetBSD, it has to be running Xen 3.1, as
979: support has not been ported to later versions at this time.
980:
981: For a PCI device to be exported to a domU, is has to be attached to the
982: `pciback` driver in domain0. Devices passed to the domain0 via the
983: pciback.hide boot parameter will attach to `pciback` instead of the
984: usual driver. The list of devices is specified as `(bus:dev.func)`,
985: where bus and dev are 2-digit hexadecimal numbers, and func a
986: single-digit number:
987:
988: pciback.hide=(00:0a.0)(00:06.0)
989:
990: pciback devices should show up in the domain0's boot messages, and the
991: devices should be listed in the `/kern/xen/pci` directory.
992:
993: PCI devices to be exported to a domU are listed in the `pci` array of
994: the domU's config file, with the format `'0000:bus:dev.func'`
995:
996: pci = [ '0000:00:06.0', '0000:00:0a.0' ]
997:
998: In the domU an `xpci` device will show up, to which one or more pci
999: busses will attach. Then the PCI drivers will attach to PCI busses as
1000: usual. Note that the default NetBSD DOMU kernels do not have `xpci` or
1001: any PCI drivers built in by default; you have to build your own kernel
1002: to use PCI devices in a domU. Here's a kernel config example:
1003:
1004: include "arch/i386/conf/XEN3_DOMU"
1005: #include "arch/i386/conf/XENU" # in NetBSD 3.0
1006:
1007: # Add support for PCI busses to the XEN3_DOMU kernel
1008: xpci* at xenbus ?
1009: pci* at xpci ?
1010:
1011: # Now add PCI and related devices to be used by this domain
1012: # USB Controller and Devices
1013:
1014: # PCI USB controllers
1015: uhci* at pci? dev ? function ? # Universal Host Controller (Intel)
1016:
1017: # USB bus support
1018: usb* at uhci?
1019:
1020: # USB Hubs
1021: uhub* at usb?
1022: uhub* at uhub? port ? configuration ? interface ?
1023:
1024: # USB Mass Storage
1025: umass* at uhub? port ? configuration ? interface ?
1026: wd* at umass?
1027: # SCSI controllers
1028: ahc* at pci? dev ? function ? # Adaptec [23]94x, aic78x0 SCSI
1029:
1030: # SCSI bus support (for both ahc and umass)
1031: scsibus* at scsi?
1032:
1033: # SCSI devices
1034: sd* at scsibus? target ? lun ? # SCSI disk drives
1035: cd* at scsibus? target ? lun ? # SCSI CD-ROM drives
1036:
1037:
1038: NetBSD as a domU in a VPS
1039: =========================
1040:
1041: The bulk of the HOWTO is about using NetBSD as a dom0 on your own
1042: hardware. This section explains how to deal with Xen in a domU as a
1043: virtual private server where you do not control or have access to the
1044: dom0.
1045:
1046: TODO: Perhaps reference panix, prmgr, amazon as interesting examples.
1047:
1048: TODO: Somewhere, discuss pvgrub and py-grub to load the domU kernel
1049: from the domU filesystem.
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